Re: Status of ReiserFS + Journalling

[Jeremy Fitzhardinge]

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On Thu, Oct 05, 2000 at 11:33:30AM +0200, Helge Hafting wrote:
> A power failure might leave you with a corrupt disk block.  That is
> detectable (read failure) and you may then reconstruct it using the
> rest of the stripe.  This will get you data from either before=20
> or after the update was supposed to happen.

How would you be able to tell which disk contains the bad stripe?
RAID reconstruction relies on knowing which disk to reconstruct because
it's obviously bad - there's out of band information in the form
of I/O errors.  If you only have an incompletely updated stripe on
a disk, you don't know which data to reconstruct from parity.

I think the only way of doing this properly is to either have
battery-backed cache, or by having journalling at the RAID level.

	J

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